1. Field of the Invention
The present invention relates to a system which provides map information via an information transmitting means such as a network (the internet, a Local Area Network (LAN) and the like).
2. Description of the Prior Art
Recently, people can obtain desired map information using terminal devices. In one method, a user accesses a storage medium such as a CD-ROM on which map information is stored, and reads out the stored map information therefrom to display it on a screen of the terminal device.
In another method, a network serving as an information transmission means, such as the internet, is used to obtain map information. There are various kinds of information services provided via the internet, including a map information searching and displaying service. In the service of this kind, the user can access a WWW server, which has a map database and is connected to the internet, to obtain desired map information and display it on the terminal device. Specifically, when the user designates an address, a place name, a station name, a name of various kinds of facilities, a shop name, and the like on the terminal device, map information of the designated place and the area around there is displayed on the terminal device as picture information. Therefore, the user can see the displayed map information to easily know the position of the station, facility and the like of interest.
However, in the above-mentioned method using the storage medium such as a CD-ROM, if map information is revised, the user should get the storage medium of the new version. In addition, such a storage medium inherently has a limit in its storage capacity, and it is sometimes difficult or impossible for the user to obtain desired map information if he or she needs map information of very broad area, such as world map, or very detailed map information.
On the other hand, in the method using the internet, such problem does not occur because the map database of the WWW server generally stores various kinds of map data. However, since the user needs to access the WWW server via the internet and download desired map information (i.e., picture data) to the terminal device, it takes certain period of time. Particularly, if the user wants map information of the area which he or she frequently uses, e.g., map information around his or her home, office or client, etc., it is troublesome to connect with the internet and download map data every time the user needs it.
In view of the above mentioned problems, it is an object of the present invention to provide a map information providing system and a map information searching method capable of quickly and efficiently obtaining desired map information at a terminal device connected to a network such as the internet.
According to one aspect of the present invention, there is provided a map information providing system for providing map data to a terminal device via a data transmission path, including: a first server, the first server including a first storage unit for storing map data; and a second server connected with the first server and the terminal device via a network, the second server including a second storage unit for storing the map data, the first server including: a unit for producing map search table which designates at least one of the first storage unit, the second storage unit and a third storage unit in the terminal device, from which certain map data is to be obtained; and a unit for transmitting the produced map searching table to the terminal device to be stored in the terminal device.
In accordance with the map information providing system thus configured, the first server produces map search table which designates at least one of the first storage unit, the second storage unit and a third storage unit in the terminal device, from which certain map data is to be obtained. Then, the first server transmits the map search table to the terminal device and make the terminal device store the map search table. Therefore, the terminal device can refer to the map searching table to determine the storage unit and access it to obtain the desired map data.
In a preferred embodiment, the map searching table may include instructions to obtain the map data of a first region from the third storage unit, to obtain the map data of a second region broader than the first region from the second storage unit and to obtain the map data of a third region broader than the second region from the first storage unit. Thus, the user can obtain the map data of relatively limited region from the third storage unit in the terminal device quickly, and obtain the map data of relatively broad region from the first or second storage unit via the network, thereby enabling quick and efficient map providing operation.
In another preferred embodiment, the map searching table may include instructions to obtain the map data of a first scale from the third storage unit, to obtain the map data of a second scale larger than the first scale from the second storage unit and to obtain the map data of a third scale larger than the second scale from the first storage unit. By this, relatively rough map information can be quickly obtained from the terminal device. Also, the detailed map information, generally having a large data capacity, is obtained from the first or second storage unit via the network. Therefore, desired map information may be quickly and efficiently obtained without excessively or unnecessarily occupying the storage capacity of the terminal device.
In a still another preferred embodiment, the map searching table may include revision information indicating revision dates of the respective map data stored in the first storage unit, the second storage unit and the third storage unit. Thus, by referring to the map searching table, the user can constantly obtain the map information of the newest version.
According to another aspect of the present invention, there is provided a map information searching method executed in a map information providing system including: a first server including a first storage unit for storing map data; a second server connected with the first server via a network and having a second storage unit for storing the map data; and at least one terminal device connected with the second server via the network and including a third storage unit for storing the map data and a map searching table map search table which designates at least one of the first storage unit, the second storage unit and a third storage unit in the terminal device, from which certain map data is to be obtained, the method including the steps of: at the terminal device, receiving from a user an input designating map data to be searched for; referring to the map searching table and determining one of the first storage unit, the second storage unit and the third storage unit, from which the map data designated by the user is to be obtained; accessing the storage unit determined by the determining step to obtain the designated map data; and displaying the obtained map data on a display device of the terminal device.
In accordance with the map information searching method, the map search table includes designations of at least one of the first storage unit, the second storage unit and a third storage unit in the terminal device, from which certain map data is to be obtained. Therefore, the terminal device can refer to the map searching table to determine the storage unit and access it to obtain the desired map data.
In a preferred embodiment, the method may further include the steps of: storing the map data of a first region in the third storage unit, storing the map data of a second region larger than the first region in the second storage unit and storing the map data of a third region larger than the second region in the first storage unit; and storing, in the map searching table, information indicating one of the storage units in which the map data is stored. Thus, the user can obtain the map data of relatively limited region from the third storage unit in the terminal device quickly, and obtain the map data of relatively broad region from the first or second storage unit via the network, thereby enabling quick and efficient map providing operation.
In another preferred embodiment, the method may further include the steps of: storing the map data of a first scale in the third storage unit, storing the map data of a second scale larger than the first scale in the second storage unit and storing the map data of a third scale larger than the second scale in the first storage unit; and storing, in the map searching table, information indicating one of the storage units in which the map data is stored. By this, relatively rough map information can be quickly obtained from the terminal device. Also, the detailed map information, generally a having large capacity, is obtained from the first or second storage unit via the network. Therefore, desired map information may be quickly and efficiently obtained without excessively or unnecessarily occupying the storage capacity of the terminal device.
In still another preferred embodiment, the method may further include the step of storing, in the map searching table, revision information indicating revision dates of the respective map data stored in the first storage unit, the second storage unit and the third storage unit. Thus, by referring to the map searching table, the user can constantly obtain the map information of the newest version.
According to still another aspect of the present invention, there is provided a map information searching method executed in a map information providing system including: a first server including a first storage unit for storing map data; a second server connected with the first server via a network and having a second storage unit for storing the map data; and at least one terminal device connected with the second server via the network and including a third storage unit for storing the map data, the method including the steps of: a first step for receiving from a user, at the terminal device, an input designating map data to be searched for; a second step for determining whether or not the designated map data is stored in the third storage unit; a third step for accessing the third storage unit to obtain the designated map data if it is determined in the second step that the designated map data is stored in the third storage unit; a fourth step for determining whether or not the designated map data is stored in the second storage unit if it is determined in the second step that designated map data is not stored in the third storage unit; a fifth step for accessing the second storage unit to obtain the designated map data if it is determined in the fourth step that the designated map data is stored in the second storage unit; a sixth step for determining whether or not the designated map data is stored in the first storage unit if it is determined in the fifth step that the designated map data is not stored in the second storage unit; a seventh step for accessing the first storage unit to obtain the designated map data if it is determined in the sixth step that the designated map data is stored in the first storage unit; and an eighth step for displaying, on a display device of the terminal device, the map data obtained in one of the third step, the fifth step and the seventh step.
In accordance with the map information searching method, storage position of the designated map data is automatically determined to be one of the first to third storage units, and the map data can be obtained by accessing the storage unit thus determined.
The nature, utility, and further features of this invention will be more clearly apparent from the following detailed description with respect to preferred embodiment of the invention when read in conjunction with the accompanying drawings briefly described below.